The header is displaying all requests (and requests per sec) and bytes since ApacheTop started. It also breaks down the response codes into 2xx (200-299), 3xx, 4xx, and 5xx buckets. Below that is the same data for recent requests (in this case the last 30 seconds, which is configurable for a given time period or a specific number of requests).

Finally there’s a list of the most requested objects. This can be sorted by any of the shown columns and also filtered by URL.

It’s on my list to rewrite this in Ruby and bring it up to date, but as I don’t currently admin any webservers of note it’s a fairly low priority.